System for 3D Image Projections and Viewing

ABSTRACT

Shaped glasses have curved surface lenses with spectrally complementary filters disposed thereon. The filters curved surface lenses are configured to compensate for wavelength shifts occurring due to viewing angles and other sources. Complementary images are projected for viewing through projection filters having passbands that pre-shift to compensate for subsequent wavelength shifts. At least one filter may have more than 3 primary passbands. For example, two filters include a first filter having passbands of low blue, high blue, low green, high green, and red, and a second filter having passbands of blue, green, and red. The additional passbands may be utilized to more closely match a color space and white point of a projector in which the filters are used. The shaped glasses and projection filters together may be utilized as a system for projecting and viewing 3D images.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/942,455 filed on Jul. 15, 2013, which is a continuation of U.S.patent application Ser. No. 12/530,379 filed on Sep. 8, 2009, which is anational application of PCT application PCT/US2008/006007 filed on May9, 2008 which claims the benefit of the filing date of U.S. ProvisionalPatent Application Ser. No. 60/931,320 filed on May 21, 2007. PCTapplication PCT/US2008/006007 is a continuation of U.S. patentapplication Ser. No. 11/804,602 filed on May 18, 2007 now is issued asU.S. Pat. No. 7,959,295. PCT application PCT/US2008/006007 also is acontinuation of U.S. patent application Ser. No. 11/801,574 filed on May9, 2007 now is issued as U.S. Pat. No. 7,784,938, all of which arehereby incorporated by reference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

TECHNICAL FIELD

The present invention relates viewing systems and products forprojecting and viewing spectrally separated 3-Dimensional (3D) images.The invention is also related to viewing systems used in a DigitalCinema (D-Cinema) Theatre and improves current methods for projectingand viewing a 3D stereoscopic movie.

BACKGROUND ART

Methods for 3D stereoscopic projection include Anaglyph, LinearPolarization, Circular Polarization, Shutter Glasses, and SpectralSeparation. Anaglyph is the oldest technology, and provides left/righteye separation by filtering the light through a two color filter,commonly red for one eye, and cyan for the other eye. At the projector,the left eye image is (commonly) filtered through a red filter, and theright image filtered through a cyan filter. The eyewear includes, forexample, a red filter for the left eye, and a cyan filter for the righteye. This method works best for black and white original images, and isnot well suited for color images.

Linear Polarization 3D provides separation at the projector by filteringthe left eye through a linear polarizer (commonly) oriented vertically,and filtering the right eye image through a linear polarizer orientedhorizontally. The eyewear includes a vertically oriented linearpolarizer for the left eye and a horizontally oriented polarizer for theright eye. The projection screen must be of the polarization preservingtype, commonly referred to as a “silver screen” because of itsdistinctive color. Linear Polarization allows a full color image to bedisplayed with little color distortion. It has several problems,

these include the need for a silver screen which is expensive, fragile,and not uniform. Another problem is that the viewer must keep his headoriented vertically to avoid crosstalk from one eye to another.

Circular Polarization 3D was invented to address the problem ofrequiring the viewer to keep his head oriented vertically. CircularPolarization provides separation at the projector by filtering the lefteye image through a (commonly) left handed circular polarizer, andfiltering the right eye image through a right handed circular polarizer.The eyewear includes a left handed circular polarizer for the left eyeand a right handed circular polarizer for the right eye. A silver screenis also needed for this approach. Shutter Glasses provides separation bymultiplexing the left and right images in time. A filter for separationat the projector is not required. The eyewear includes Shutter Glasses.These are active glasses that electronically shutter the lens insynchrony with the projector frame rate. The left eye image is firstdisplayed, followed by the right eye image etc. Since having a directwired connection to the Glasses in a theatre is impractical, a wirelessor infrared signaling method is used to provide a timing reference forthe left/right eye shuttering. This method requires an IR or RFtransmitter in the auditorium. The Shutter Glasses are expensive andhard to clean, require batteries that must be frequently replaced, andare limited in their switching rate. Shutter glasses are only practicalfor use with D-Cinema or other electronic projection systems since veryfew film projectors provide the signal required to synchronize theshutter glasses with the frame rate. The method does not require asilver screen.

Spectral Separation provides separation at the projector by filteringthe left and right eye spectrally. The system differs from anaglyph inthat the filters for the left and right eye each pass a portion of thered, green, and blue spectrum, providing for a full color image. Theband pass spectrum of the left eye filter is complementary to the bandpass spectrum of the right eye filter. The eyewear includes filters withthe same general spectral characteristics as are used in the projector.While this method provides a full color image, it requires colorcompensation to make the colors in the left and right eye match thecolors that were present in the original image, and there is a smallreduction in the color gamut compared to the gamut of the projector.

All of the above methods for providing left/right eye separation for a3D Stereoscopic presentation can be used with either two projectors (onefor the left eye and one for the right eye), or may be used with asingle D-Cinema projector system. In the dual projection system, theprojection filter is usually static, and is located in front of theprojection lens. In a single D-Cinema projector system, the left andright images are time multiplexed. Except for the Shutter Glasses casewhere no projection filters are required, this means that the projectionfilters must change at the L/R multiplex frequency. This can be donewith either a filter wheel in the projector synchronized to themultiplex frequency, or with an electronically switched filter.

DISCLOSURE OF THE INVENTION

The present inventors have realized the need for improvements inspectrally separated viewing devices and systems. The invention providesseveral techniques to remove and compensate for blue shift that occurswhen viewing images through filters at off-axis (other than normal)angles. The blue shift is undesirable because it can result in crosstalkbetween left and right images in a 3D image presentation.

The present inventors have also realized the need for improvements inspectral separation filters, and particularly those used in 3D D-Cinemaapplications. One problem realized is that typical 3-D projectionsystems have low luminance efficiency in that color spaces, color gamut,and effective brightness are inadequate. Another problem realized isthat imbalance between luminance levels in channels of 3D projectionsdecreases luminal efficiency. Accordingly, as described in more detailbelow, the present invention also provides techniques to increase thecolor space and luminal efficiency of projected images that may be usedalone or in combination with blue shift compensation techniques.

The present invention includes one or more techniques to increase thecolor space of spectrally separated images which may be combined withone or more techniques to compensate for blue shift that occurs whenviewing spectrally separated images through filters at other than normalangles. The individual techniques are further described herein.

When utilized together, the invention is a system comprising a 3Dprojection device using asymmetric projection filters and viewingglasses comprising non-flat lenses with spectrally complimentaryfilters.

Generally described, in one embodiment, the present invention provides apair of 3D spectral separation filters (eye filters), disposed on leftand right lenses of a pair of viewing glasses, the eye filterscomprising a combination of increased (and proportional to wavelength)guard bands, and appropriately curved lenses to reduce crosstalk, colorshift, and reflections at the edge of the field of view. A blue shiftedcolor filter in a

-   -   A—projector that projects images for viewing through the glasses        may also be utilized.

Although the present invention encompasses a combination of improvementsto viewing glasses and preparation of images for viewing (e.g., imageprojection), the invention may be practiced with less than all theimprovements in combination. In one embodiment, the present inventioncomprises viewing filters comprising a non-flat substrate and spectrallycomplementary filters.

In one embodiment, the present invention provides spectral separationviewing glasses, comprising, a first lens having a first spectralfilter, and a second lens having a second spectral filter complementaryto the first spectral filter, wherein the first lens and the second lensare each curved to reduce the wavelength shift that occurs when viewingan image at other than an angle normal to a filter through which theimage is being viewed. An amount of curvature of the lenses (and hencethe filters) is calculated such that viewing angles across a viewingscreen are closer to normal angles through the lenses. The curvature isimplemented, for example, as a spherical curve. In another embodiment,the invention is embodied as spectral separation viewing glasses,comprising, a first lens comprising a first spectral filter, and asecond lens comprising a second spectral filter complementary to thefirst spectral filter, wherein the first spectral filter and the secondspectral filter have at least one guard band between adjacent portionsof spectrum of the spectral filters. The guard band has a bandwidthsufficient to remove crosstalk of spectrally separated images viewedthrough the glasses, and, for example, is calculated based on an amountof wavelength shift occurring when viewing portions of the spectrallyseparated images at an angle through the filters.

In one embodiment, the present invention provides a spectral separationviewing system, comprising, viewing glasses having both curved lensesand increased guard bands, and a projection system configured to projectfirst and second spectrally separated images wherein the images arewavelength pre-shifted to compensate for wavelength shifts occurringduring display and/or viewing of the images. Such systems are preferablyimplemented in a commercial movie theater, but are also applicable tolarge screen televisions, computers, virtual reality systems, and otherdisplay devices. The present invention includes a method, comprising thesteps of, projecting first and second spectrally separated images onto adisplay screen, viewing the projected images through a pair of glasseshaving a first lens having a first spectral filter matching the firstspectrally separated image and a second lens having a second spectralfilter matching the second spectrally separated image, wherein thespectral filters are

configured to have a varying amount of wavelength shift effect dependingupon a viewing angle through the lens.

In one embodiment, the present invention is a 3D viewing system,comprising, means for projecting spectrally separated images, means forviewing the spectrally separated images through different ocularchannels, and means for compensating for wavelength shifts occurring dueto viewing angles to portions of the images. The means for compensatingmay include, for example, means for adjusting an amount of spectralfiltering performed on different portions of the image based on viewingangle. The means for compensating includes, for example, means forproducing a wavelength mismatch between projector filters and eyefilters that compensates for an amount of wavelength shift that occursin the eye filters due to viewing angle.

The present invention may also be described as shaped glasses,comprising a pair of spectrally complementary filters disposed on curvedlenses of the glasses. The spectrally complementary filters may includeguard bands between adjacent spectrums of the spectrally complementaryfilters. In one embodiment, the thickness of dielectric layers of thespectrally complementary filters increases toward edges of the lenses.

The present invention includes a method, comprising the steps of,distributing shaped glasses to audience viewers, and projecting firstand second spectrally complementary images on a display screen withinview of the audience members, wherein the shaped glasses comprise firstand second shaped lenses having first and second spectrallycomplementary filters respectively disposed thereon. In one embodiment,the first and second spectrally complementary filters respectivelycorrespond in bandwidth to the projected first and second spectrallycomplementary images. However, the filters are not necessarily requiredto correspond exactly with the projected images of the filters. Theshaped glasses comprise, for example, spherically shaped lenses.

The present invention includes a storage medium having at least a visualperformance stored thereon, that, when loaded into a media playercoupled to a display device, causes the media player to transmit thevisual performance for display to the display device; wherein the visualperformance as displayed on the display device is configured for viewingthrough a pair of shaped glasses. The storage medium is, for example,prepackaged with at least one pair of shaped glasses and available forpurchase via a retail outlet.

In yet another embodiment, the present invention is a system for viewing3D images, comprising, serving 3D content over a network to a receivingelectronic device, and displaying the 3D content, wherein the 3D contentcomprises spectrally complementary images intended to be viewed withspectrally separated shaped glasses. The receiving electronic device is,for example, a display system located at a movie theater.

The present invention addresses some of the problems with the SpectralSeparation method for projecting 3D images, specifically an improvementin the efficiency, increase in the color gamut, and a reduction in theamount of color compensation required. In some cases, the colorcompensation may not be required. The present invention addresses theefficiency and color space issues by splitting primary colors of theprojector into subparts. The splitting of primary colors into subpartsis accomplished in part through the filter installed in the projector,which is the main controlling factor in the color space of the system.The efficiency and color gamut of the projected image are both increasedusing the additional subparts of the split primary colors.

In one embodiment, the present invention provides a projector filter,comprising, a first filter having a first set of primary passbands, anda second filter having a second set of primary passbands, wherein thefirst set of primary passbands has a different number of primarypassbands than the second filter. The first filter has, for example, atleast two blue primary passbands and the second filter has at least oneblue primary passband. The first filter may also have, for example, atleast two green primary passbands and the second filter has at least onegreen primary. For example, the first filter may have passbandwavelengths of approximately 400 to 440 nm and 484 to 498 nm, 514 to 528nm, 567 to 581 nm, and 610 to 623 nm, and the second filter may havepassband wavelengths of approximately 455 to 471 nm, 539 to 556 nm, and634 to 701 nm. The passbands of the first filter and the second filterare, for example, selected to maximize reproduction of a color space ofa D-Cinema projector.

The present invention may also be realized as a system for projection ofspectrally separated 3D images, comprising, a projection systemconfigured to project left and right channel images for display by aviewer, a filter placed in at least one light path of the projectionsystem comprising a left channel filter and a right channel filter,wherein at least one of the left and right channel filters has more than3 primary passbands. In one embodiment, one of the left and rightchannel filters has at least 2 primary passbands in

blue wavelengths and one of the left and right channel filters has atleast 2 primary passbands in green wavelengths. Again, the primarypassbands of the filters are selected to maximize reproduction of acolor space of the projection system in images projected by theprojection system. The system may include, for example, a colorcorrection module configured to color correct images projected by theprojection system according to a color space of the filters.

The invention may also be embodied as a set of filters, comprising afirst filter having a first set of primary color passbands, a secondfilter having a second set of primary color passbands of differentwavelengths compared to the first set of primary colors, wherein thefirst filter has more than one primary color in at least one color band.

The present invention may also be embodied as a method, comprising thesteps of, preparing a 3D image comprising a left image and a rightimage, filtering the left image with a left channel filter, filteringthe right image with a right channel filter, and projecting the left andright filtered images onto a screen, wherein at least one of the leftchannel filter and right channel filter have more than 3 primarypassbands. As in all of the above described embodiments, the filters(e.g., filters used in performing the steps of filtering) may themselvesbe embodied in an electronically switchable filter set, fixed filters ina two projector system, or a filter wheel wherein approximately ¹A thewheel has filter characteristics of a left channel filter according tothe present invention and approximately Vi the wheel has filtercharacteristics of a right channel filter according to the presentinvention.

Portions of the invention may be conveniently implemented in programmingon a general purpose computer, or networked computers, and the resultsmay be displayed on an output device connected to any of the generalpurpose, networked computers, or transmitted to a remote device foroutput or display. In particular, the invention includes the utilizationof software that implements color processing separately on each ocularchannel. Any components of the present invention represented in acomputer program, data sequences, and/or control signals may be embodiedas an electronic signal broadcast (or transmitted) at any frequency inany medium including, but not limited to, wireless broadcasts, andtransmissions over copper wire(s), fiber optic cable(s), and co-axialcable(s), etc.

DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1A is an illustration of viewing angles;

FIG. 1B is graph illustrating spectrum of left projector filter andright eye filter;

FIG. 2 is a graph illustrating spectrum of left projector filter vs.blue shifted right eye filter;

FIG. 3 is a graph illustrating spectrum of blue shifted left projectorfilter vs. blue shifted right eye filter;

FIG. 4A is a diagram illustrating geometry of curved lenses centered ata viewer's pupil;

FIG. 4B is an illustration of glasses with spherical lenses;

FIG. 5 is a diagram illustrating geometry of curved lenses and showingchild interpupillary distances;

FIG. 6 is a diagram illustrating geometry of curved lenses for 20 degreeangle at an edge of the lenses;

FIG. 7 is a diagram illustrating geometry of curved lenses withnon-spherical curve;

FIG. 8 A is a diagram illustrating effect of lens curvature on lightcoming from behind a viewer;

FIG. 8B is a drawing of dihedral angles for a pair of viewing glasses.

FIG. 9 is a drawing illustrating glass frames configured for use ondifferent sized heads.

FIG. 10 is a diagram illustrating geometry of optimized dihedralglasses.

FIG. 11 is a graph of conventional left and right spectral separationfilters.

FIG. 12 is a 1931 CIE chromaticity diagram illustrating the color spaceof a typical Digital Cinema (D-Cinema) projector.

FIG. 13 is a 1931 CIE chromaticity diagram illustrating the color spaceof conventional spectral separation filters.

FIG. 14 is a graph of left and right projector filters.

FIG. 15 is a 1931 CIE chromaticity diagram illustrating the color spaceof color filters.

FIG. 16 is a graph of left and right eyeglass filters that may beapplied in conjunction with the projector filters described in FIG. 4.

FIG. 17A is a block diagram of a projection.

FIG. 17B is a drawing of a filter wheel; and

FIG. 18 is a drawing of a fixed filter arrangement in a two projectorsystem.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention addresses some of the problems with the SpectralSeparation method for projecting 3D images, specifically this inventionaims to improve the off-axis filter characteristics when thin filmdielectric (interference) filters (e.g., right eye and left eye filters)are used to implement eyewear (e.g., glasses) for viewing spectrallyseparated images.

When light passes through an interference filter at a non-normal angle,the filter characteristics (response shapes, not to be confused with thephysical shape of the filter) are changed, and the entire spectralfilter response is shifted toward shorter wavelengths (toward the blue).The filter characteristic response shapes are also adversely affected atlarger angles. This is a fundamental attribute of interference filters,and can be compensated for by designing the filter for a specific angleif all of the rays are parallel. In cases where the light bundle is notparallel, as in the case with the use of 3-D glasses, solutionsinvolving only design of the filter characteristics are less practical.

Glasses currently used for spectral separation consist of flatinterference filters located about 2 cm in front of the viewer's eyes.In a 3D Cinema theatre (e.g. 3D D-Cinema) the light from the screen doesnot pass through the interference filters at a single angle. For aviewer located center and one screen width back, when viewing the imageat the center of the screen, the light from the center of the screenwould pass through the interference filters of the glasses at a normal(perpendicular) angle (assuming the viewer's head is positioned suchthat the plane of the interference filters is parallel to the plane ofthe screen). Under similar conditions, light from the edge of the screenwould pass through the interference filters at an angle of about 26degrees.

This viewing position is reasonably close to the screen, but is notabnormal; many of the seats in a common auditorium are located closer,and angles of 40 degrees are possible. A 26 degree angle from the edgeof the screen would have the effect of shifting the filter responsetoward the blue by about 14 nanometers (nm), and would somewhat distortthe filter shape. The resulting 3D image appears to have noticeablecolor shift and increased left/right eye crosstalk towards the edges ofthe screen. The invention uses a combination of several techniques toreduce the effects of the blue shift, and to reduce the blue shiftoccurring from non-normal viewing angles. It should be remembered thatthe blue shift at the interference filters (e.g., lenses of the glasseshaving filters disposed thereon) is primarily important because itcauses a mismatch between spectral characteristics of the projectorfilter (e.g., a filter wheel or electronically switched filter) and theglasses, or more precisely, a mismatch between the spectra of lightforming the images (from whatever source) and the characteristics of theglasses at a given viewing angle.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts, and more particularly to FIG. 1Athereof, there are illustrated example viewing angles through glasses1110 for a viewer 1100 of an image projected onto a movie screen 1120.The viewing angles range from normal to somewhat oblique (e.g.,approximately θi to θ_(3>) respectively). The glasses 1110 includelenses with dielectric based interference filters. The non-normalviewing angles have an amount of blue-shift associated with the viewedimage that increases with greater obliqueness of the viewing anglethrough the interference filters. For example, light entering the user'seyes from the more oblique angles θ₂ and θ₃ will be shifted toward bluewavelengths whereas the more normal angle θi will have little, if any,blue shift. The blue shift, or wavelength shift, so described resultsfrom a shift in the interference filter properties such that the lightbands passed by the filter are shifted toward shorter wavelengths. Oneeffect of the blue shift of light viewed at the edge of the screen(e.g., light

1130) is to introduce crosstalk in the image. This can be reduced byincreasing the guard bands between left eye and right eye filtercharacteristics. FIG. 1 B illustrates characteristics of exemplaryfilters used for 3D spectral separation. As shown in FIG. 1B, bandwidthsfor a left projection filter 100, and a right eye filter 110, includesguard bands 120, 122, 124, 126, and 128 which appear as notches betweenadjacent light bands (FIG. 1 B illustrates the right eye filter and theleft projection filter; the right eye filter approximately representsbandwidths of the right projection filter and the left projection filterapproximately represents bandwidths of the left eye filter). Byincreasing the width of the notch (or guard band) between left and rightspectra in both the eye filters and the corresponding projector filters,crosstalk can be reduced. This also reduces the perceived color shift.This method also reduces the optical efficiency of the system, but thistradeoff may be made.

As can be seen in FIG. 1 B, as a pair, the left and right eye filtersare complementary in that the filter properties of the left eye filter(approximately represented by the left projection filter 100) complementthe filter properties of the right eye filter 110. It is not a fullcomplement in that the guard bands, keep the combined filters frompassing the entire portion of the spectrum between the longest andshortest wavelengths passed by the filters. Further, additionaldifferences in bandwidth within the ranges of the various bands passedby the filters may be made so as to accommodate engineering decisionsregarding color space issues that need to be addressed for a particularapplication.

Another approach is to pre-blue shift characteristics of the projectorfilter, or red shift the eye filters, such that for viewing at a normalangle of incidence through the eye filters, the filter characteristicsare red shifted with respect to the projector filter. This increases thecrosstalk and color shift for normal (on axis) viewing, but this can betuned such that for on axis viewing the crosstalk and color shift is notobjectionable. For the off axis case, the performance is improved sincethe difference between the projector filters and the blue shifted(off-axis) eye filters is lower. FIG. 2 and FIG. 3 describe thissituation. As shown in FIG. 2, a left projector filter 200, and a blueshifted right eye filter 210 have guard bands including guard band 220separating adjacent bands of light). As shown in FIG. 3, a blue shiftedleft projector filter 300 and a blue shifted right eye filter 310 haveguard bands including guard band 320 separating adjacent bands of light.As seen by comparing FIG. 2 and FIG. 3, the notch (guard bands 210 and310) separating the adjacent bands of light is larger in FIG. 3.

Applying this to the case described earlier, the shift of 14 nm at theedges of the screen could be reduced to an effective shift of 11 nm ifthe projector filter were shifted blue 3 nm. There would be a “redshift” of 3 nm at the center of the screen.

Another approach is to curve the filters, which can be implemented, forexample, by disposing the eye filters on curved lenses of viewingglasses. This has the advantage that it has the potential of actuallyreducing the blue shift.

FIG. 4A describes the geometry of curved lenses with a radius centeredat the eye pupil. The lenses shown (lens 405 A having optical axis 410Aand lens 405B having optical axis 410B) have a width of 50 mm and thechord is located 20 mm from a

respective pupil (and center of curvature) (e.g., 400A and 400B). Themeasurements were made for the inventor's eyes, but are representativeof the general situation that could be implemented for anyone wearing 3Dglasses. Using glasses with lenses having a spherical section with aradius centered on the entrance pupil of the eye virtually eliminatesany blue shift in the filters because the light passes through thelenses (and hence, the filters) virtually normal to the lens/filter forviewing all parts of the screen. Some distortion occurs when the viewerturns his eyes to look at different parts of the screen, but for thegeometry shown, this is not significant. FIG. 4B illustrates two viewsof a pair of glasses 490 having curved lenses 492 A and 492B which areboth spherically shaped and having spectrally complementary dielectricfilters disposed thereon (left eye filter 496A and right eye filter496B).

The curvatures of the lenses so implemented are distinguished fromprescription glasses in that the implemented curvatures are not tocorrect vision. Nevertheless, in one embodiment, the curvature of theinvention may be implemented over or in addition to other lenscharacteristics intended to fulfill a viewer's prescription needs.

The curved lens solution still has some limitations. First, the radiusof curvature of 30 mm resulting from the geometry described aboveappears very “bug-eyed,” and would be esthetically unpleasing. Second,this curvature would produce glasses whose weight would be centered wellin front of the nosepiece, and they would be poorly balanced. Third,this radius may be too short to allow uniform coating of an interferencefilter.

Fourth, the interpupillary distance of eyes varies significantly, andthis would mean that glasses designed for the mean would be improperlycurved for someone with other than the mean distance. For example, witha child the situation may result in an angle of about 10 degrees forviewing of the center of the screen. As shown in FIG. 5, the location ofa child's pupils (510A and 510B) and the resulting optical axis of thechild's eye (530A and 53OB) is displaced off the corresponding opticalaxis of the glasses (520A and 520B respectively centered at center ofcurvatures 500A and 500B).

Even considering the limitations associated with curving the lensesand/or filters, this technique is valuable. Although in general cases orproductions for mass audiences, it may not make sense to attempt to havethe radius of curvature centered directly at the entrance pupil of theeye. By making the lenses spherical but with a radius of curvaturecentered behind the entrance of the pupil of the eye, much of theproblems are removed (e.g., bringing the center of gravity back towardthe viewer, and a less “bug-eyed” appearance) and the advantages aresignificantly retained.

In one alternative, the lenses may use a non-spherical curvature, suchas a cylindrical curvature where the lenses are only curved from left toright, and there is no curvature in the vertical direction. This ispossible because the screens always have an aspect ratio such that thehorizontal extent (e.g., width) is about twice the vertical extent(e.g., height). Another alternative is to use a curvature that is nonspherical in either direction, such as a multiple radius surface, or onethat follows a specific mathematical function. These have advantages forallowing a greater interpupillary variation. An additional advantage ofcurved lenses includes the reduction of reflections from bright surfacesbehind the viewer, since these reflections are not directed toward theeye.

A final approach involves the design of the interference filters. Thisapproach requires changing the thickness of the dielectric layers as afunction of the distance from the center of each eye filter. If thethicknesses of the dielectric layers are increased at the edges of thefilters such that they cause a red shift in the filter characteristics,this can be used to compensate for the blue shift caused by the anglechange at the edges of the field of view through the filters.

If the filters are implemented on flat glass, the thickening of thedielectric layers may increase manufacturing costs due to difficulty inimplementing the increased thicknesses at different points on the flatglass. However, when coating on a curved surface, some thickening occursduring the coating process. This approach therefore becomes a practicaladjunct to the curved lens solution.

The best method for achieving high performance with interference filtersincorporates the four techniques described above in the followingmanner. First, the guard bands between left and right eye filters shouldbe greater than approximately 2% (e.g., 2.2%) of the wavelength of thatfilter band. For example, for a filter with a left/right crossover at640 nm, the guard band should be approximately 14 nm. Second, theprojector filter should be designed to be blue shifted (with respect tothe eye glass filters) greater than 0.6% of the wavelength of the filterband. In the same example, the center of the guard band for theprojector filter would be 640−3.8=636.2 nm. The combination of theseallow nominally manufactured lenses and eye filters (when used with anominally manufactured projector lens and projector filters) to betilted such that a blue shift of 18 nm occurs before serious degradationof the image occurs.

However, the combined manufacturing tolerance from the projector filtersand the eye filters reduces this to about 9 nm. The 9 nm guard band thatremains can be used for accommodating the blue shift caused by the lightgoing through the left and right eye filters at an angle. The anglethrough the left and right eye filters that causes a 9 nm shift is about20 degrees. If the curvature of the eye filters (e.g. curvature oflenses upon which the eye filters are disposed or incorporated) isadjusted to allow the light from the edge of the eye filters to passthrough to the eye at a maximum of 20 degrees relative to the normal ofthe eye filters at the edge, then serious degradation of the image atthe edge of the eye filters will not occur. For a simple sphere, andwith the eye looking straight at the center of the screen

(e.g., a primary gaze normal to a tangent of the lens), the radius ofcurvature needed to achieve this is approximately 50 mm. As shown inFIG. 6 (lenses 605A and 605B have respective centers of curvature 610Aand 610B; adult pupil locations at 615A, 615B and corresponding opticalaxis of the lenses and adult eye 630A and 630B; child pupil locations at620A, 620B and corresponding optical axis of child's eye 635A and 635B).In practice the radius of curvature may be somewhat greater than 50 mmto accommodate the pupil shift when the eye is turned to observe theside of the picture screen.

Although spherically shaped lenses are preferred, non-spherical lensesdo have some advantages. FIG. 7 shows left and right lenses 705A and705B with a non-spherical curve (adult pupils 700A, 700B; optical axisof the lenses 715A, 715B; child pupils 710A, 710B, and correspondingoptical axis of child's eye 720A, 720B). The left and right lensesincorporate corresponding left and right eye filters. The filters are,for example, disposed on one or more surfaces of the lenses. Theadvantages of a non-spherical curve are found in accommodatingvariations of interpupillary distances between different viewers.Finally, a non-uniform dielectric coating can be used to red shift thefilter characteristics at the edges of the filters, further improvingthe performance.

A more important advantage is that reflections from behind the viewerare reduced by the curvature. This is important because the interferencefilters disposed on the eyeglass lenses reflect light that is nottransmitted, and are therefore quite reflective. Without the curve, theaudience behind the viewer is visible across much of the back side ofthe lens. With the curve, only a portion (or none) of the lens has areflection from behind the viewer. FIG. 8 illustrates this advantage bycomparison of a curved lens 705 having a center of curvature at 708 anda flat lens 710. With respect to the flat lens 710, a relatively wideangled light ray 725 from behind the viewer is reflected off the flatlens into the viewer's pupil 700A. With respect to the curved lens 705,it is shown that only a relatively narrow angle (light ray 720) canreach the viewer's pupil 700B via reflection from the curved lens. Inaddition, the viewer's temple 730 blocks most light rays sufficientlynarrow to enter the viewer's temple. Further optimization of thetechniques discussed can be achieved by accommodating interpupillarydistance variation among the population. In general, interpupillaryspacing is directly related to head width and girth. Adults have largerwidth and girth, and wider interpupillary spacing, while children aresmaller in these dimensions. Ideally, a viewer would wear glasses withthe left and right eye filters disposed on corresponding left and rightlenses of the glasses where the interocular spacing of the lenses isoptimized for the viewer's particular interpupillary distances.

In a theatre or other large volume application, it is cumbersome tostock different sized glasses. As an optimization to the curved glassesit is possible to incorporate a feature into the design of the frame ofthe glasses that automatically adjusts a dihedral angle between thecurved lenses to accommodate wider and narrower interpupillary spacing.Adjusting the dihedral angle insures a close to normal light incidencewhen viewing the screen with a primary gaze. This adjustment is done byexploiting the flexibility and bending strength properties of moldedthermoplastic frames, or other frames having similar properties ofstrength and flexibility (e.g., metals, fiberglass, composites, etc).

In this design there is an outward convexity to the shape of the frames,which creates a dihedral angle between the lenses. In one embodiment,the bridge of the glasses is designed to flex slightly with head sizevariation due to pressure on the frame (e.g., pressure exerted on thetemple portion of the frames). This flexing results in dihedral anglechanges. As shown in FIG. 8B, wider heads 875 with (statistically)larger interpupillary spacing have a larger dihedral angle θ_(A) In thiscontext, the dihedral angle is defined as the angle between a planesextending through endpoints on opposite ends of the lenses (see dashedline in FIG. 8B). Smaller heads 880 would have a smaller dihedral angleθβ. With a smaller head and corresponding smaller dihedral angle betweenthe lenses, the distance between the forward directed radii of thecurved lenses is reduced to more closely match the smallerinterpupillary spacing.

FIG. 9 illustrates both cases. Glasses 900 are illustrated in a firstposition 900A as when worn by an adult with a relatively larger sizedhead. Interpupillary spacing of the adult is represented by Y. A templeor “around the ear” portion of the frame of the—glasses have a spacingrepresented by Y′ to accommodate the adult's head size, causing a flexof the bridge 910 of the glasses and resulting in a larger dihedralangle between the lenses.

Position 900B, is similar to that when worn by a child with a relativelysmaller sized head, and the interpupillary distance of the child isrepresented by X. The bridge 910 is less flexed because the temple or“around the ear” spacing is reduced to X′ which results in a smallerdihedral angle between the lenses. The smaller dihedral angleaccommodates the child's smaller interpupillary spacing as describedabove.

FIG. 10 illustrates details for the lenses. At 1005, an adult right eyepupil 101OA is shown relative to a child's eye pupil 1015A), with thelens 1020 having a center of curvature at 1025A. As seen in FIG. 10,comparing the position of lens 1020 to lens 1030 in position 1030A, alarger dihedral exists between the lenses. This is the appropriate lensconfiguration for an adult.

When worn by a child (or person with a relatively smaller sized head),an amount of flex of the bridge of the glasses cause lenses 1030 and1020 to decrease in dihedral as illustrated by 1050 for the left eye(consistent with FIG. 9, a similar dihedral decrease (not shown) occursfor the right eye in lens 1020). The center of the radius of curvature(1040 for lens 1030 in position 1030B) has shifted from an alignmentcorresponding to the adult pupil IOIOB to an alignment corresponding tothe child's pupil 1015B. FIGS. 8B, 9, and 10 are illustrative of anaccommodation for both “adult sized” and “child sized” heads andinterpupillary distances. However, it should be understood thatinterpupillary distances and head sizes vary amongst the entirepopulation. While near perfect alignment may occur for some viewers, itis not required and the embodiments illustrated function to accommodatethe varying head sizes and interpupillary distances by improving theviewing angle alignments in most cases.

The lenses shown in FIG. 10 have a 50 mm radius of curvature and thedihedral angle is 2 degrees. With conventional sized frames the dihedralangle change for the average adult verses child is about 5 degrees(approximately 2.5 degrees accounted for on each side of the frames fora total of about 5 degrees). This technique works best with lenses witha radius of curvature that is about half the length of the templeportion of the glasses.

As noted above, the present invention addresses some of the problemswith the Spectral Separation method for projecting 3D images,specifically an improvement in the efficiency, increase in the colorgamut, and a reduction in the amount of color compensation required. Insome cases, the color compensation may not be required.

Referring again to the drawings, and more particularly to FIG. 11thereof, there is illustrated a set of left and right spectralseparation filters representative of those currently used in D-Cinema3-Dimensional (3D) presentations. As shown in FIG. 11, the conventionalspectral separation filters provide three primaries for each eye bydividing the red, green, and blue color channels of a projector into twosets of primaries, one set for the left eye (primaries 111OR, HOG, and11OB) and one set for the right eye (primaries 1112R, 1112G, and 1112B).For example, the left eye is illustrated as having shorter wavelengthblue, green, and red bands than the right eye. Following a conventionaldesign, the left eye may have, for example, passband wavelengths ofapproximately 400 to 445 (blue), 505 to 525 (green), and 595 to 635(red). The right eye may have, for example, passband wavelengths ofapproximately 455 to 495 (blue), 535 to 585 (green), and 645 to 700(red). While a filter configuration like that illustrated in FIG. 11provides all three colors to each eye, the resulting image has asomewhat different hue in each eye. In order to make the images moreclosely match the colors for each eye, and match the colors in theoriginal image, color correction is applied. The color correctionreduces the overall efficiency of the system (since it boosts someprimaries preferentially over others). In addition, even with colorcorrection, the new left and right primaries do not have as large of acolor space as the projector, and thus can only produce a portion, butnot every color that would be present if projected without the filtersin a 2D system.

FIG. 12 is a 1931 CIE chromaticity diagram illustrating the unfilteredcolor space 1200 and P3 white point 1210 of a typical Digital Cinema(D-Cinema) projector. The unfiltered color space of the projectorrepresents the color space available for projecting images.

FIG. 13 is a 1931 CIE chromaticity diagram illustrating the color spaceof conventional spectral separation filters used to separate the lefteye channel 1320 and right eye channel 1330 in a D-Cinema projector. Theintersection of the left and right eye channel color spaces representsthe potential color space of images projected through the filters. Ascan be seen in FIG. 13, the potential color space using the conventionalfilters is restricted compared with the projector color space (1200,FIG. 2). In addition, the P3 white point 1310 is an important factor inthe overall result of the projected image, and is significantly shiftedcompared to that of the projector alone—see P3 white point 1315 for theleft eye and P3 white point 1325 for the right eye and compare toprojector P3 white point 1210, shown for reference in FIG. 13.

The present invention pertains to the filter installed in the projector,which is the main controlling factor in the color space of the system.The invention addresses both the efficiency and the color space issuesby splitting at least one of the projector primaries into subparts. Inone embodiment, the blue and green projector primaries are split intothree sub-parts each. The exact wavelengths of where the primary issplit may be chosen in any manner that takes into account the particularcolor space to be reproduced.

For example, as shown in FIG. 14, in one potential configuration, aright channel projection filter has passband wavelengths of blue at 400to 440 (410-B1) and 484 to 498 nm (410-B2), green at 514 to 528(1410-G1) and 567 to 581 nm (1410-G2), and red at 610 to 623 nm(1410-R). A left channel projection filter has passbands wavelengths ofblue at 455 to 471 nm (1412-B), green at 539 to 556 nm (1412-G), and redat 634 to 700 nm (1412-R). Of course other permutations exist, such as,for example, switching the left and right channel wavelengths, orswitching the green and blue wavelengths etc. In addition, the passbandwavelengths are approximate and each band may vary by, for example +/−5nm or more. Such variations may occur by shifting the entire passbandand/or by selecting one or more different endpoints for the passbands.An important consideration is that such variances should not reduce theguard band between passbands to a level where a system using the filtersincurs unacceptable levels of crosstalk between the channels.

The selection of passband wavelengths is made such that when an image isprojected with a D-Cinema projector with a P3 white point 1210 and colorspace 1200 as, for example, shown in FIG. 12, the resultant color spacein the channels, and more particularly the combined color spaces of theprojected images, have a color space and white point that more closelymatch the color space 1200 and P3 white point 1210 compared to the colorspace and white point that occurs when using conventional spectralseparation, such as shown in FIG. 13. The passbands are also chosen tomaximize efficiency by selecting passbands that will result in havingapproximately the same, or balanced, luminance levels in each channel.So long as sufficient bandwidth is available in each passband to achievethe stated improvements (as, for example, proven by experimentalresults), there are no theoretical limits on the variances that mayoccur over the example passband wavelengths described herein.

Note that there are gaps in the spectrum of colors that did not exist inthe previous design (for example between 498 nm and 514 nm for blue togreen transition in the right channel, and between 581 nm and 610 nm forthe green to red transition in the right channel). These notches aredesigned to increase the color space so that it matches the P3 colorspace in D-Cinema projectors. The filter response needed to get thecorrect P3 result was derived using the real (measured) spectralresponse from the D-Cinema projectors, which is reflected in the chosenwavelengths for the passbands described above.

Also note that in the illustrated example, the three sub-parts arestructured such that they are interleaved between the right and leftchannels. From a practical standpoint, this means that the threesub-parts are arranged such that one filter has at least one sub-partlower and one sub-part higher than the sub-part of the other filter. Forexample, in FIG. 14, the blue passbands of the right channel projectionfilter straddle the blue passband of the left channel projection filter.Such interleaving is preferably maintained in the various embodiments,including those embodiments that divide passbands into more than 3sub-parts. Although theoretically there is no limit on the number ofsub-parts in which any passband may be divided, due to cost and otherfactors, a point of diminishing returns is quickly reached and 3sub-parts each of blue and green and 2 sub-parts of red appears to havethe greatest return with reasonable cost. With improved componentsand/or reduced costs of components, a different economic analysis mayresult and 4, 5, or more sub-parts, including additional sub-parts inthe red, may be justified for additional incremental increases in thecolor space. Such incremental improvements might also be justified undercurrent economic and cost models for upper end equipment markets. FIG.15 shows the color space diagrams for the filters of this inventiondescribed above. As can be seen in FIG. 15, the intersection, orproduct, of the left channel projection filter color space and rightchannel projection filter color space results in a color space moreclosely matching the color space 1200 (FIG. 12) than which occurs withconventional spectral separation. Some portions of the color space arereduced and other portions of the color space are increased. Althoughsome areas of the color space are reduced, the reduced areas are lessimportant to viewers. Areas of the color space to which viewers are moresensitive have made significant gains with the invention versusconventional spectral separation.

Glasses used to view the projected images need not be as complex as theprojector filter since the notches that provide the improved color spacehave no impact on the left/right eye (or left/right channel) separation,and therefore the notches do not need to be reproduced in the viewingfilters of the glasses (the projector filter has more bands, andtherefore more complexity than the viewing filters). As shown in FIG.16, in one configuration the right eye lens of the glasses would have afilter with passband wavelengths of approximately 430 to 440 nm (part ofthe blue band), 484 to 528 nm (part of the blue, and part of the greenband), 568 to 623 (part of the green band and the red band), whichencompass the passbands of the right channel projector filter. The lefteye lens of the glasses would have a filter with passband wavelengths of455 to 471 (blue), 539 to 555 nm (green), and 634 to 700 nm (red) whichencompass the passbands of the left channel projector filter.Wavelengths below the beginning wavelengths in the blue (approximately430 nm) and wavelengths above ending wavelengths in red (approximately700 nm) are beyond the visible spectrum and may either be included orexcluded from the passbands. Other permutations exist as describedbefore (including left/right channel exchange), but the left and righteye lenses of the glasses include corresponding permutations thatencompass or match the left and right channel projector filterpermutations.

Along with other factors such as projector color space and white point,the final images viewed through the glasses are a product of theprojecting filters and viewing filters (e.g., filters in the glassesused to view the images). In the described embodiments, the receivingfilters are less demanding as far as passband design because they havefewer notches and they generally encompass more wavelengths in at leastsome of the passbands. The important role played by the glasses isseparation of the entire images as whole and as projected, not specificbands within each image as described for the projection filters.

The overall response (color space and white point) to the eye is theproduct of the spectral response of the projector filter(s), thelenses/filters of the eyeglasses, and the base D-Cinema projectorresponse (color space and white point of the D-Cinema projector withoutthe left and right channel projector filters). Nevertheless, the colorspace is mostly defined by the position of the passbands and the notchesin the yellow and blue-green bands, and therefore the overall responseis mostly a function of the projector filter (because the glasses do notneed and preferably do not have the notches).

In part, because of the lower complexity of the eyeglass (or viewing)filters, the eyeglass filters are also comparatively less expensive toproduce compared to the projection filters. This is a benefit becausethe eyeglass filters are generally embodied as a pair of glasses worn byviewers (including the general public), and are therefore likely to besubjected to less than perfect care, whereas the projector equipmentincluding the projector filters are generally kept in more secure andstable environments. In addition, the glasses are generally purchased inlarger numbers than the projector filter(s).

Another aspect of the differing complexities of the eyeglass (orviewing) filters compared to the projector filters is that they createan asymmetric filtering system. That is, each viewing filter and itscorresponding projection filter of the same channel are not symmetric inbandwidth and/or the number of passbands. The passbands of the viewingfilters may also entirely encompass the passbands of the projectionfilters (and, in some embodiments, the passbands of the projector filtermay be blue-shifted relative to the passbands of the viewing filters toaccount for viewing angle related blue shifts in the viewing filters).Regardless of whether the projection filters are entirely encompassed bythe passbands of the viewing filters, the passbands of the viewing andprojection filters preferably are different. Therefore, a preferredresult is an asymmetric filtering system.

The particular projector filter response used in describing theinvention uses 3 divisions of the blue and green projector color bands.The red band is divided into two parts (one part for the right channeland one part for the left channel). Additional divisions may be utilizedfor increased color space, but additional cost of the filters may beincurred. Careful selection of the optical passbands provides a closematch to the color space and white point of the original unfilteredprojector. The design of the glasses is such they have the samecomplexity of the conventional spectral separation design, but provideadequate selectivity to minimize crosstalk between the images projectedin the left and right channels.

FIG. 17A is a block diagram of a projection system 1700 according to anembodiment of the present invention. The projection system 1700 includesa digital cinema projector 1705 that projects spectrally separated 3Dimages (a left channel image and a right channel image) throughprojection filter 1730 and projection lens 1720 onto a screen 1710 forviewing with glasses 1715. Glasses 1715 include, for example spectrallyseparated filters disposed as coatings on each lens of the glasses suchthat the right lens comprises a filter that matches or encompasses thepassbands of the right channel filter and the left lens comprises afilter that matches or encompasses passbands of the left—channel filter(each of the left and right channel images are intended to be viewed bya viewer's corresponding left or right eye through the correspondingleft or right eye lens/filter of the glasses). The glasses 1715, andsystem 1700, may, for example, include any of the features, systems, ordevices described in Richards et al, a U.S. patent application entitledMETHOD AND SYSTEM FOR SHAPED GLASSES AND VIEWING 3D IMAGES, Ser. No.11/801,574, filed May 9, 2007, the contents of which are incorporatedherein by reference as if specifically set forth.

The projector 1705 receives image data for projection from a server1780. 3D content is provided to the server 1780 from, for example, adisk drive 1740. Alternatively, 3D content may be transmitted toprojector 1705 over a secure link of network 1755 from, for example, animage warehouse or studio 1750. Multiple other projectors (e.g., attheaters around the globe, 1760! . . . 176O_(n)) may also feed fromsimilar network or other electronic or wireless connections includingwireless networks, satellite transmission, or quality airwave broadcasts(e.g., High Definition or better broadcast). The server 1780 includescolor correction module 1775 that performs mathematical transformationsof color to be reproduced by the projector prior to image projection.The mathematical transformations utilize image data for each of the leftand right channels and transform them into parameters consistent withthe primary colors or passbands of the corresponding left or rightchannel filter. The mathematical transformation, or color corrections,adjust the hue of each image and maximize the available color space andmatch the color space and white point of projector 1705 as closely aspossible.

The amount of color correction required when using the invention issignificantly reduced when compared with conventional spectralseparation.

The color corrected 3D content is transmitted to projector 1705. The 3Dcontent includes left and right channel images that switch at a ratefast enough that they blend into a single 3D image when viewed by aviewer through glasses 1715. At some point in the optical path of theprojection system, filters according to the present invention areutilized. For example, a filter wheel 1730 is placed at point in theoptical path closer to the light source. FIG. 17B provides anillustrative example of a filter wheel 1730 in front, side, and angleviews. Specifications for appropriate physical dimensions andcharacteristics of the exemplary filter wheel 1730 include, for example:an outside diameter (OD) 1732 of 125.00 mm+/−0.15 mm, an inside hole1734 with a diameter (ID) of 15.08 mm+/−0.04 mm (that is, for example,off-center by not more than 0.075 mm), and a thickness of 1.00 mm-1.20mm. The exemplary filter wheel includes, for example, Material:Borofloat or Fused Silica, Monolithic Filter, 2 Section (e.g., TYPE A, afirst channel filter, and TYPE B, a second channel filter), Max 3 mmUndefined Transition, Clear Aperature: 1 mm From OD, 10 mm From ID,Surface Quality: 80-50 Where Scratch Number is Width Measured InMicrons. Edge Finish: As Fabricated, Edge Chips: Less Than Or Equal To 1mm. All such specifications are exemplary and other combinations ofmaterials, dimensions, and/or construction techniques, etc, may beutilized. Alternatively, an electronically switched filter 1725 isplaced, for example, after the projection lens 1720.

A controller 1735 provides signals that maintain synchronization betweenthe filter 1730 and the image being projected. For example, features ofa left channel filter according to the present invention are active whena left channel image is being projected, and features of a right channelfilter according to the present invention are active when a rightchannel image is being projected. In the electronically switched filtercase, the controller signals switching between left and right channelfilters in synchronicity with the left and right image projections. Inthe filter wheel embodiment, for example, the controller maintains arotational speed and synchronicity between the left and right channelimages and the left and right channel filters respectively. The blendedimage as viewed through glasses 1710 has a color space and white pointthat closely matches a color space and white point of projector 1705without filter 1730. The present invention includes an embodiment inwhich a filter wheel having left and right channel projection filtersdisposed thereon is placed inside a movie projector between the lightsource and integrating rod of the movie projector. The advantage of thisplacement is that the amount of light passing through the remainingoptical components is reduced and less likely to overload sensitiveelectronics or other components (e.g. DLP, LCOS, or other lightprocessors or light valves in the projector), but the amount of lightthat exits the projection is system is equivalent to embodiments wherethe projection filter(s) is placed further downstream locations.Alternatively, the power of the light source can be increased resultingin increased output without jeopardizing the integrating rod or otherdownstream components. Further advantages to the described placement ofthe filter is that the filter can be made smaller than at most otherpoints in the light patch, and at a reduced cost compared to largerfilters. And, images formed after filtering are generally found to besharper than images formed and then filtered.

In one embodiment, the projection filter is a filter wheel whereapproximately ¹A the wheel has filter characteristics of a left channelfilter according to the present invention and approximately ¹A the wheelhas filter characteristics of a right channel filter according to thepresent invention. Table 1 specifies an exemplary filter wheelspecification for a multi-band filter having a left channel filtersection and right channel filter section. The Delta values shown inTable 1 specify a slope (steepness) of the band edges. The T50 valuesspecify the wavelength at the band edge where the light transmission is50%. At the band pass wavelengths the transmission is at least 90%, andat the band reject wavelengths the transmission is less than 0.5%. Thewheel may have, for example a diameter of approximately 125 mm diameterwhich is well suited for installation in a D-Cinema projector (e.g.,projector 705) between the light source and integrating rod.

Table 1

The above exemplary specifications include some pre-blue-shiftingconsistent with the above-cited Richards et al patent application.However, inclusion of blue-shifting and other features is not required.

Table 2 specifies an exemplary set of viewing filters matching (orencompassing the passbands of the projector filters but also including asmall amount of red shift). The filters include a multi-band filter forthe left channel (or left eye lens) and a multi-band filter for theright channel (or right eye lens). The Delta values specify the slope(steepness) of the band edges. The T50 values specify the wavelength atthe band edge where the light transmission is 50%. At the band passwavelengths the transmission is at least 90%, and at the band rejectwavelengths the transmission is less than 0.5%. These filters are, forexample, placed on left and right lenses of glasses 1715.

Table 2

FIG. 18 is a drawing of a fixed filter arrangement in a two projectorsystem 1800 according to an embodiment of the present invention. Leftand right channel images are derived, decoded, retrieved, orreconstructed from data stored on disk drive 1840 (or received from anappropriate network or transmission reception) by server 1880. Colorcorrection as described above may also be applied (not shown).

The decoded, color corrected (if applicable), left and right channelimages are then projected simultaneously from left and right channelprojectors 1805A and 1805B onto screen 1810 for viewing through glasses1715. A right channel filter 1820A having passband characteristics asdescribed above is used to filter the projected right channel image. Aleft channel filter 1820B having passband characteristics as describedabove is used to filter the projected left channel image. The right andleft channel filters are fixed filters (e.g., filters withcharacteristics that do not change with time), and are constructed, forexample, from a clear substrate (e.g., glass) coated with appropriatelayers to produce the passbands for the desired left or right channelfilter characteristics. The fixed filter may be located in the projectorat any point in the optical path, or may be located outside theprojector past the projection lens as shown in FIG. 18.

Although the present invention has been mainly described as increasingcolor space by increasing the number of passbands in the blue and greenwavelengths (and interleaving those passbands between the left and rightchannels), the invention should not be limited to increasing the numberof passbands in the same number or in the same wavelengths asspecifically described herein, and, should include any number ofincreased passbands at any wavelength capable of being passed by theprojection filter. For example, instead of dividing the blue primaryinto three sub-parts (2 subparts in one channel and one part in theother channel); the blue primary may be divided into four or moresub-parts (e.g., 3 sub-parts in one channel and 2 sub-parts in the otherchannel). Further, division of sub-parts as described herein may beperformed at any of the available wavelengths and can therefore beextended into the red wavelengths. Further yet, discussion above shouldnot be viewed to limit implementations of wherein the additionalsub-parts of the blue and green bands are necessarily in the samechannel, as the invention can be practiced by having two sub-parts ofblue in a first channel, one sub-part of blue in a second channel, twosub-parts of green in the second channel, and one sub-part of green inthe first channel. The same also logically extends to embodiments withmore than three sub-parts where the additional subparts may be in any ofthe color hands and any of the channels.

In yet another example, the recitations regarding curved glass lenseshaving a 50 mm radius of curvature is exemplary and any other radiicould be utilized so long as the radius does not extend toward infinity(making the glasses flat, or essentially flat). For example a 40 mmradius or an 80 mm radius or more (e.g., even up to 200 mm) may providesuitable alternatives and not detract an unacceptable amount from thebenefits of the described 50 mm radius of curvature. In one embodiment,a radius of curvature of the glass lenses is 90 mm (alternatively,approximately 90 mm) which represents an acceptable trade-offconsidering the cost and difficulty of coating lenses with a greateramount of curvature without detracting too substantially from thebenefits of optimally curved lenses.

Various non-limiting and exemplary embodiments of the invention are nowdescribed, including, for example, viewing glasses comprising a non-flatsubstrate (e.g., non-flat lenses), with spectrally complementary filters(alternatively, the filters are for two channels such that the filter ofa first channel passes light hands of the first channel and blocks lighthands of the second channel and visa-versa). The viewing glasses maycomprise, for example, a first lens having a first spectral filter, anda second lens having a second spectral filter complementary to the firstspectral filter, and the first and second lenses are each curved toreduce a wavelength shift that occurs when viewing an image at otherthan a normal angle through the lens. In various embodiments, the curveof each lens comprises, for example, any of: a radius centered on theviewers pupil, a radius centered behind the viewers pupil, anon-spherical shape, a cylindrical shape, includes multiple radii, apredetermined mathematical function, prescription curvatures. In oneembodiment, the spectral filters have a thickness that varies bylocation on the lens. In another embodiment, the spectral filterscomprise a plurality of dielectric layers, and the dielectric layershave an increased layer thickness toward edges of the lenses. In anotherembodiment, the present invention comprises viewing filters comprising anon-flat substrate and spectrally complementary filters. In oneembodiment, at least one of the spectrally complimentary filterscomprises, for example, a single passband configured to pass twolightbands of different colors. In one embodiment, at least one of thespectrally complimentary filters comprises a single passband configuredto pass two different colors of light. In one embodiment, the spectrallycomplimentary filters are configured for viewing a 3D display, which,for example, may comprise a reflection off a cinema screen. In oneembodiment, the spectrally complimentary filters comprise, for example,a first filter having a set of primary passbands comprising, a firstpassband configured to pass both a green lightband and a red lightband,and a second passband configured to pass both a blue lightband and agreen lightband. In one embodiment, the spectrally complimentary filterscomprise, a first filter comprising a first set of primary passbandscomprising a passband configured to pass both a green lightband and ared lightband, and a second filter comprising a second set of primarypassbands comprising a passband configured to pass both a blue lightbandand a green lightband. In one embodiment, the spectrally complimentaryfilters comprise a first filter having a set of 3 passbands configuredto pass a set of more than 3 primary color lightbands. In oneembodiment, the spectrally complimentary filters comprise a first filtercomprising a first set of passbands configured to pass a first set ofprimary lightbands and a second filter comprising a second set ofpassbands configured to pass a second set of primary lightbands, whereinthe first set of primary lightbands are mutually exclusive to the secondset of primary lightbands. Additionally, the first set of passbands andthe second set of passbands may be, for example, separated by guardbands having a width calculated to maintain separation between theprimary lightbands when viewed through the viewing filters andcompensate for blue shift due to a viewing angle of the primarylightbands through the viewing filters. In one embodiment, at least oneof the passbands encompasses at least two of the primary lightbands.

In another embodiment, the invention comprises spectral separationviewing glasses, comprising, a first lens comprising a first spectralfilter, and a second lens comprising a second spectral filtercomplementary to the first spectral filter, wherein the first spectralfilter and the second spectral filter have at least one guard bandbetween adjacent portions of spectrum of the spectral filters, and theguard band bandwidth is calculated based on an amount of blue shiftoccurring when viewing portions of the spectrally separated images at anangle through the lenses. In one embodiment, the guard band has abandwidth sufficient to reduce crosstalk of spectrally separated imagesviewed through the glasses. The guard band comprises, for example,approximately 2% or more of a wavelength of a crossover point ofadjacent portions of the spectral filters.

In another embodiment, the invention comprises a spectral separationviewing system, comprising, viewing glasses, comprising a first lenshaving a first spectral filter, and a second lens having a secondspectral filter complementary to the first spectral filter, wherein thespectral filters include a guard band between adjacent portions ofspectrum of the first and second lenses, and the lenses have a curvatureconfigured to cause angles of incidence of light at edges of the lensesto be closer to normal when compared to flat lenses. The curvature ofthe lenses are, for example, spherical. In one embodiment, the spectralfilters are not uniform across the lenses. In various other embodiments,the viewing system further comprises, for example, a projection systemconfigured to project first and second spectrally separated images, andthe first and second spectrally separated images are each respectivelyviewed through the spectral filters of the viewing glasses. The viewingsystem may also further comprise, for example, a plurality of pairs ofsaid viewing glasses, each pair of viewing glasses being assigned to anindividual viewer in a movie theater audience, and the first and secondfilters are disposed on lenses of each pair of glasses.

In yet another embodiment, the invention comprises a method, comprisingthe steps of, projecting first and second spectrally separated imagesonto a display screen, viewing the projected images through a pair ofglasses having a first lens having a first spectral filter designed tobe used with the first spectrally separated image and a second lenshaving a second spectral filter designed to be used with the secondspectrally separated image, and wherein the spectral filters areconfigured to have an amount of wavelength shift effect depending upon aviewing angle through the lens. In one embodiment, adjacent portions ofspectrum of the first and second spectral filters are separated by aguard band comprising a bandwidth calculated for a central viewinglocation and sufficient to eliminate crosstalk for normal viewing fromedges of the display screen. In yet another embodiment, the spectralfilters comprise a plurality of guard bands each separating a differentset of adjacent spectrums in the first and second filters, and abandwidth of each guard band is determined based on a function of acrossover wavelength of the adjacent spectrums and a viewing angle to anedge of the display screen. The display screen is, for example, a cinemamovie screen.

In yet another embodiment, the present invention comprises a 3D viewingsystem, comprising means for projecting spectrally separated images,means for viewing the spectrally separated images through differentocular channels, and means for compensating for wavelength shiftsoccurring due to viewing angles to portions of the images. In oneembodiment, the means for compensating includes, for example, means foradjusting an amount of spectral filtering performed based on viewingangle. In another embodiment, the means for compensating includes, forexample, means for producing a wavelength mismatch between projectorfilters used to project the spectrally separated images and eye filtersused to view the spectrally separated images, wherein the mismatchcompensates for an amount of wavelength shift that occurs in the eyefilters due to light incident upon the eye filters at non-normal angles.In yet another embodiment, the present invention comprises a viewingsystem, comprising shaped glasses comprising a pair of left and rightspectrally complementary filters respectively disposed on left and rightcurved lenses of the glasses, and a display system configured to displayspectrally separated left and right images respectively configured to beviewed through the left and right complimentary filters, wherein eachspectrally separated image comprises at least one light bandwidthapproximately matching at least one pass band of its correspondingfilter. The display system further comprises, for example, a projectorconfigured to display the spectrally separated left and right imageswith a pre-determined amount of pre-blue shift. In one embodiment, thespectrally complementary filters comprise guard bands between adjacentspectrums of the spectrally complementary filters. The shaped glasses ofthe viewing system, are, for example, utilized to view color shiftedprojections of spectrally complementary images. In one embodiment, theshaped glasses of the viewing system include frame temples and a bridgedesigned to flex implementing an adjustable dihedral angle between thelenses.

An amount of the dihedral angle change due to flexing is, for example,approximately 5 degrees.

In yet another embodiment, the present invention comprises a method,comprising the steps of, distributing shaped glasses to audiencemembers; and projecting first and second spectrally complementary imageson a display screen within view of the audience members, wherein theshaped glasses comprise first and second shaped lenses having first andsecond spectrally complementary filters respectively disposed thereon,and the first and second spectrally complementary filters respectivelycorrespond in bandwidth to the projected first and second spectrallycomplementary images. In one embodiment, the bandwidth correspondence ofthe first spectrally complimentary filter passes colors in a firstchannel of a projection and blocks colors in a second channel of theprojection, and the bandwidth correspondence of the second spectrallycomplimentary filter passes colors in a second channel of a projectionand blocks colors in a first channel of the projection. In yet anotherembodiment, the present invention comprises a storage medium having avisual performance stored thereon, that, when loaded into a media playercoupled to a display device, causes the media player to transmit thevisual performance for display to the display device, wherein the visualperformance comprises spectrally separated images configured to beviewed respectively through independent ocular channels using curvedspectrally separated filters. The storage medium is, for example,prepackaged with at least one pair of glasses having curved lenses uponwhich the curved spectrally separated filters are disposed. Thespectrally separated images are, for example, displayed by the displaydevice using filters that are blue shifted compared to filtering thatoccurs through normal angle viewing of the curved spectrally separatedfilters. The spectrally separated images are, for example, separated bya guard band configured to compensate for spectra mismatch between theprojected images and properties of filters used to view the projectedimages. The combination of pre-blue shifting, curved lenses, and guardbands effectively eliminates crosstalk when viewing the images.

In yet another embodiment, the present invention comprises, for example,a system for viewing 3D images, comprising, serving 3D content over anetwork to a receiving electronic device, projecting the 3D content to adisplay device, wherein the 3D content comprises spectrallycomplementary images intended to be viewed with shaped glasses. Thereceiving electronic device comprises, for example, a display systemlocated at a movie theater. In one embodiment, the projected 3D contentis projected with a predetermined amount of blue-shift.

In yet another embodiment, the present invention comprises a method ofdisplaying an 3-D image, comprising the steps of, projecting left andright filtered images onto a screen, and filtering the left and rightimages for each of spectrally specific properties corresponding to theimage prior to display on the screen, wherein the filtering is performedwith a filter having characteristics that are shifted an amountconfigured to compensate for a wavelength shift that occurs when aviewer watches the screen. The wavelength shift comprises, for example,a blue-shift that occurs due to viewing angles (which may be, forexample, a blue-shift that occurs in characteristics of an eye filterused to view the images, or, as another example, a blue-shift occurringin filtered viewing glasses when viewing any of the images through thefiltered viewing glasses at other than a normal angle). The spectrallyspecific properties corresponding to the image comprise, for example, aset of wavelengths corresponding to the right images and a complimentaryset of wavelengths corresponding to the left images.

In yet another embodiment, the present invention comprises a projectorfilter, comprising, a first filter having a first set of primarypassbands, and a second filter having a second set of primary passbands,wherein the first set of primary passbands has a different number ofprimary passbands than the second filter. In one embodiment, the firstfilter has, for example, at least two blue primary passbands and thesecond filter has at least one blue primary passband. In anotherembodiment, the first filter has, for example, at least two greenprimary passbands and the second filter has at least one green primary.In another embodiment, the first filter has, for example, two blueprimaries and two green primaries and the second filter has one blueprimary and one green primary. In another embodiment, the first filterhas, for example, passband wavelengths of approximately 400 to 440 nmand 484 to 498 nm, 514 to 528 nm, 567 to 581 nm, and 610 to 623 nm. Thesecond filter has, for example, passband wavelengths of approximately455 to 471 nm, 539 to 556 nm, and 634 to 700 nm. The passband wavelengthspecifications have a tolerance of, for example, approximately +−5 nm.In one embodiment, the primary passbands of the first filter excludeswavelengths passed by the second filter. In one embodiment, the primarypassbands of the filters are selected to maximize reproduction of acolor space of a projector. The projector color space is, for example,the color space of a D-Cinema projector. In one embodiment, theprojector filter is an electronically switchable filter that switchesbetween the first and second filters according to an imagesynchronization signal.

In yet another embodiment, the present invention comprises a system forprojection of spectrally separated 3D images, comprising, a projectionsystem configured to project left and right channel images for displayby a viewer, a filter placed in at least one light path of theprojection system comprising a left channel filter and a right channelfilter, wherein at least one of the left and right channel filters hasmore than 3 primary passbands. In one embodiment, one of the left andright channel filters has at least 2 primary passbands in bluewavelengths. In one embodiment, one of the left and right channelfilters has at least 2 primary passbands in green wavelengths. In oneembodiment, one of the left and right eye channel filters has at least 2primary passbands in blue wavelengths and at least 2 primary passbandsin green wavelengths. In one embodiment, the primary passbands of thefilters are selected to maximize reproduction of a color space of theprojection system in images projected by the projection system. In oneembodiment, the system further comprises a color correction moduleconfigured to color correct images projected by the projection systemaccording to a color space of the filters. Alternatively, the colorcorrection module is configured to color correct images based on a colorspace of light passed by the filter.

In yet another embodiment, the present invention comprises a pair ofprojector spectral separation filters configured to divide a blueprojector primary into three sub-parts, a green projector primary intothree sub-parts, and a red projector primary into to two sub-parts. Oneof the filters has, for example, two passbands in blue, two passbands ingreen, and a single passband in red, and the other filter has onepassband in blue, one passband in green, and one passband in red. Inanother embodiment. One of the filters has, for example, two passbandsin blue, two passbands in green, and only one passband in red, and theother filter has only one passband in blue, only one passband in green,and only one passband in red. In one embodiment, one of the filters has,for example, two passbands in blue, one passband in green, and onepassband in red, and the other filter has one passband in blue, twopassbands in green, and one passband in red. In another embodiment, oneof the filters has, for example, two passbands in blue, only onepassband in green, and only one passband in red, and the other filterhas only one passband in blue, two passbands in green, and only onepassband in red. In one embodiment, one of the filters has one passbandin blue, two passbands in green, and one passband in red, and the otherfilter has two passbands in blue, one passband in green, and onepassband in red. In another embodiment, one of the filters has only onepassband in blue, two passbands in green, and only one passband in red,and the other filter has two passbands in blue, only one passband ingreen, and only one passband in red. In one embodiment, the sub-partpassbands are located to achieve a substantial match to an originalcolor space and white point of an unfiltered D-Cinema projector.

In yet another embodiment, the present invention comprises, for example,a set of color filters, comprising, a first filter having a first set ofprimary color passbands, a second filter having a second set of primarycolor passbands of different wavelengths compared to the first set ofprimary colors, wherein the first filter has more than one primary colorin at least one color hand. The filter set is embodied, for example, asan electronically switchable filter set. In one embodiment, the colorfilter set is part of a 3D projection system and the primary passbandsof the first and second filters are selected to maximize reproduction ofa color space of the 3D projection system without the first and secondfilters. In yet another embodiment, the present invention comprises, forexample, a method, comprising the steps of, preparing a 3D imagecomprising a left image and a right image, filtering the left image witha left channel filter, filtering the right image with a right channelfilter, and projecting the left and right filtered images onto a screen,wherein at least one of the left channel filter and right channel filterhave more than 3 primary passbands. One of the left and right channelfilters comprises, for example, 2 primary passbands in blue wavelengthsand 2 primary passbands in green wavelengths. In one embodiment, themethod further comprises, for example, a step of viewing the projected3-D image through left and right viewing filters having passbands thatrespectively exclude passbands of the right channel filter and the leftchannel filter. In another embodiment, the method further comprises, forexample, a step of switching the left and right channel filters insynchronicity with the projection of left and right channel images ofthe 3D image.

In yet another embodiment, the present invention comprises, for example,a 3D viewing system comprising a first asymmetric filter set comprisinga projection filter and a viewing filter. In one embodiment, the 3Dviewing system may further comprise, for example, a second asymmetricfilter set wherein the first asymmetric filter set is positioned in anoptical path of the system and configured to pass wavelengths of a firstchannel of the system and the second filter set is configured to passwavelengths of a second channel of the system. In another embodiment,the viewing filter includes passbands that encompass passbands of theprojection filter. In yet another embodiment, the viewing filterincludes, for example, passbands that approximately encompass passbandsof the projection filter; and the passbands of the projection filter areblue-shifted compared to the passbands of the viewing filter. In yetanother embodiment, the present invention comprises an asymmetric filtersystem, comprising, a first set of filters comprising a first set ofoptical passbands, a second set of filters comprising a second set ofoptical passbands different from the first set of optical passbands andencompassing the first set of optical passbands. In one embodiment, thefirst set of filters is upstream in an optical path relative to thesecond set of filters. In another embodiment, the first set of filterscomprise a projection filter and the second set of filters comprise aviewing filter. In another embodiment, the first set of opticalpassbands comprises a right channel set of optical passbands and a leftchannel set of optical passbands that exclude any portion of the rightchannel set of optical passbands. In another embodiment, the second setof optical passbands include a left channel set of optical passbands anda right channel set of optical passbands that exclude any portion of theleft channel optical passbands.

In yet another embodiment, the present invention comprises a method,comprising the steps of, providing a theater audience with a pair of 3Dviewing glasses comprising left and right lenses respectively comprisingleft and right viewing filters, and projecting left and right imagesonto a display screen using left and right projection filters, whereinthe left projection filter and the left viewing filter comprise a firstasymmetric filter set and the right projection filter and the rightviewing filter comprise a second asymmetric filter set. In oneembodiment, a total number of passbands in the viewing filters is lessthan a total number of passbands in the projection filters. In oneembodiment, the projector filters comprise passbands that divide bluelight wavelengths into at least three blue sub-parts and that dividegreen wavelengths into at least two green sub-parts. In one embodiment,a viewing filter in one of the asymmetric filter sets comprises apassband that encompasses wavelengths in the longest wavelength bluesub-part and wavelengths in a green sub-part. In one embodiment, theprojector filters comprise passbands that divide green light wavelengthsinto at least three sub-parts and divide red light into at least two redsub-parts, and a viewing filter in one of the asymmetric filter setscomprises a passband that encompasses a longest wavelength greensub-part and a red sub-part. In one embodiment, the projector filterscomprise passbands that divide blue light wavelengths into at leastthree sub-parts and green light wavelengths into at least threesub-parts, and a viewing filter in one of the asymmetric filter setscomprises a passband that encompasses a longest wavelength blue sub-partand a shortest wavelength green sub-part. In one embodiment, theprojector filters comprise passbands that divide green light wavelengthsinto at least three sub-parts and red light wavelengths into at leastthree sub-parts, and a viewing filter in one of the asymmetric filtersets comprises a passband that encompasses a longest wavelength greensub-part and a shortest wavelength red sub-part. In one embodiment, eachviewing filter comprises, three passbands exclusively comprising onepassband including blue wavelengths, one passband including greenwavelengths, and one passband including red wavelengths. In oneembodiment, the projector filters comprise 3 passbands each in green andblue light wavelengths and two passbands in red wavelengths. In oneembodiment, the viewing filters each exclusively comprises threepassbands, one passband of blue wavelengths, one passband of greenwavelengths, and one passband of red wavelengths. Other exemplaryembodiments have been provided throughout the present disclosure. In yetanother embodiment, the present invention comprises a filterconfigurable in an eyewear device of a spectrally separated 3D viewingsystem, comprising a set of passbands and blocking bands configured topass light wherein at least one of the passbands is capable of passingbands of 2 different colors of light and the blocking bands areconfigured to block light in at least one band of light in each of the 2different colors. In one embodiment, the passband capable of passingbands of 2 different colors of light does not pass light in a thirdcolor. In one embodiment, the bands of 2 different colors of light areseparated by a notch. The notch is, for example, a band (a notch band)not utilized by the 3D viewing system for light transmission. In oneembodiment, the notch band is, for example, relatively narrow comparedto the bands of 2 different colors of light. In another embodiment, thenotch band bandwidth is similar to a bandwidth of at least one of thebands of 2 different colors of light. In one embodiment, the notch bandencompasses a transition from wavelengths of a first of the 2 differentcolors of light to wavelengths of a second of the two different colorsof light. In one embodiment, the 2 different colors of light compriseblue light and green light and the third color comprises red. In oneembodiment, the 2 different colors of light comprise red light and greenlight and the third color comprises blue. In one embodiment, the filteris disposed on a curved substrate. In one embodiment, the filter isdisposed on a curved substrate having a radius of approximately 90 mm.In one embodiment, the filter is disposed on a curved lens having aradius of approximately 40 mm to 200 mm.

In one embodiment, the present invention comprises a filter comprisingonly 3 mutually exclusive passbands of visible light, a first passbandconfigured to pass only a first color of light, a second passbandconfigured to pass 2 spectrum adjacent colors of light comprising thefirst color of light and a second color of light, and a third passbandconfigured to pass 2 spectrum adjacent colors of light comprising thesecond color of light and a third color of light. In one embodiment, thefirst second and third colors of light are, for example, blue, green,and red, respectively. In another embodiment, the first, second, andthird colors of light are red, green, and blue, respectively. The filteris, for example, disposed on a lens configurable as a channel filter ina pair of 3D viewing glasses.

In describing the preferred embodiments of the present inventionillustrated in the drawings, specific terminology is employed for thesake of clarity. However, the present invention is not intended to belimited to the specific terminology so selected, and it is to beunderstood that each specific element includes all technical equivalentswhich operate in a similar manner.

For example, when describing a projector filter, any other equivalentdevice or device having an equivalent function or capability, whether ornot listed herein, may be substituted therewith. In another example,when describing a dielectric layer, any other material used as filterand exhibiting a substantive wavelength shift (e.g., nano-materialcoatings), whether used alone or in combination with others so as tohave an equivalent function or capability, whether or not listed herein,may be substituted therewith. In another example, a flexible bridgepiece may be substituted with any mechanism suitable to adjust adihedral angle of the lens, including a ratchet mechanism, spring loadedstops, etc. In yet another example, lenses according to the presentinvention may be constructed of glass, plastic, or any other suchmaterial providing the appropriate shapes as described above.

Furthermore, the inventors recognize that newly developed technologiesnot now known may also be substituted for the described parts and stillnot depart from the scope of the present invention. All other describeditems, including, but not limited to lenses, layers, filters, wheels,screens, display devices, passbands, coatings, glasses, controllers,projectors, display screens, networks or other transmissioncapabilities, etc should also be considered in light of any and allavailable equivalents.

The present invention may suitably comprise, consist of, or consistessentially of, any of element (the various parts or features of theinvention) and their equivalents as described herein. Further, thepresent invention illustratively disclosed herein may be practiced inthe absence of any element, whether or not specifically disclosedherein. Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

Portions of the present invention may be conveniently implemented usinga conventional general purpose or a specialized digital computer ormicroprocessor programmed according to the teachings of the presentdisclosure, as will be apparent to those skilled in the computer art(e.g., controlling an electronically switched pre-blue shift projectionfilter).

The present invention includes a computer program product which is astorage medium (media) that includes, but is not limited to, any type ofdisk including floppy disks, mini disks (MD's), optical discs, DVD,HD-DVD, Blue-ray, CD-ROMS, micro-drive, and magneto-optical disks, ROMs,RAMs, EPROMs, EEPROMs, DRAMs, VRAMs, flash memory devices (includingflash cards, memory sticks), magnetic or optical cards, SIM cards, MEMS,nanosystems (including molecular memory ICs), RAID devices, remote datastorage/archive/warehousing, or any type of media or device suitable forstoring instructions and/or data. The present invention includessoftware for controlling aspects of the present invention including, forexample, switching of pre-blue shifted filters or performance of colorcorrection stored on any computer readable medium (media).

In addition, such media may include or exclusively contain contentprepared or ready for display according to the present invention. Suchcontent is, for example, read from the media and then transmittedelectronically over a network, broadcast over the air, or transmitted bywire, cable or any other mechanism. Ultimately, the content of suchmedia may be provided to a display device and then viewed in accordancewith one or more aspects of the invention. The content is, for example,prepared or optimized so as to project images having bandwidthsoptimized for the display and viewing processes described herein. Suchmedia may also be packaged with glasses and/or filters preparedaccording to one or more of the various aspects of the invention asdescribed above.

The present invention may suitably comprise, consist of, or consistessentially of, any of element (the various parts or features of theinvention, e.g. shaped lenses, varying dielectric layer thicknesses,pre-shifting projected or displayed images, etc., and/or anyequivalents. Further, the present invention illustratively disclosedherein may be practiced in the absence of any element, whether or notspecifically disclosed herein. Obviously, numerous modifications andvariations of the present invention are possible in light of the aboveteachings. It is therefore to be understood that within the scope of theappended claims, the invention may be practiced otherwise than asspecifically described herein.

What is claimed is:
 1. (canceled)
 2. Glasses for viewing 3D images, theglasses comprising filters disposed on lenses of the glasses, thefilters configured to pass a plurality of light wavelengths intended tocarry the 3D images, and wherein spectral properties of the filters varyfrom one location to another location of the lenses.
 3. The glassesaccording to claim 2, wherein the spectral properties of the filters aredifferent at an edge of the lenses compared to a central area of thelenses.
 4. The glasses according to claim 3, wherein the spectralproperties are red shifted at the edge of the lenses compared to acentral area of the lenses.
 5. The glasses according to claim 3, whereinthe spectral properties shift toward longer wavelengths as a lens istraversed from the central area to an edge of the lens.
 6. The glassesaccording to claim 3, wherein the filters comprise at least one notchfilter.
 7. The glasses according to claim 3, wherein the filterscomprise a plurality of notch filters.
 8. The glasses according to claim3, wherein the filters comprise at least one blocking filter.
 9. Theglasses according to claim 3, wherein the glasses are part of a 3Dimaging system at a venue displaying cinema content using a plurality ofdigital cinema projectors.
 10. The glasses according to claim 2, whereinthe filters are curved, and a combination of the variance in spectralproperties and curvature counteract adverse viewing effects caused byviewing the 3D images at a an off-normal angle of incidence away from acentral area of the filters.
 11. The glasses according to claim 10,wherein passbands of a first of the filters correspond to a firstchannel image of the 3D images and passbands of a second of the filterscorrespond to a second channel of the 3D images, and wherein the glassesare part of a 3D imaging system at a venue displaying cinema contentusing a plurality digital cinema projectors.
 12. The glasses accordingto claim 10, wherein the filters comprise passbands whose spectralproperties encompass and are offset relative to wavelengths of lightintended to be viewed through the passbands.
 13. The glasses accordingto claim 2, wherein the filters comprise passbands whose spectralproperties are offset relative to wavelengths of light intended to bepassed through the passbands when the wavelengths are normally incidentto the lenses.
 14. The glasses according to claim 13, wherein the offsetcomprises an offset toward longer wavelengths.
 15. The glasses accordingto claim 13, wherein the offset comprises a red shift in the spectralproperties of each passband.
 16. The glasses according to claim 13,wherein the spectral properties of the passbands encompass the lightwavelengths intended to carry the 3D images.
 17. The glasses accordingto claim 13, wherein passbands of a first of the filters correspond to afirst channel image of the 3D images and passbands of a second of thefilters correspond to a second channel of the 3D images.
 18. Glasses forviewing an image displayed in a set of narrowband wavelengths, theglasses comprising filters disposed on lenses of the glasses, thefilters configured to pass the set of narrowband wavelengths, whereinspectral properties of the filters are shifted toward longer wavelengthsrelative to the set of narrowband wavelengths.
 19. The Glasses accordingto claim 18, wherein the shift toward longer wavelengths comprises awavelength dependent shift such that longer wavelength pass areas of thefilters have a different amount of shift compared to shorter wavelengthpass areas of the filters.
 20. The Glasses according to claim 18,wherein the filters comprise guardbands between pass areas of a filterdisposed on a first lens of the glasses and pass areas of a filterdisposed on a second lens of the glasses.
 21. The Glasses according toclaim 18, wherein longer wavelength pass areas are shifted more thanshorter wavelength pass areas.
 22. The Glasses according to claim 18,wherein the glasses comprise 3D viewing glasses and the limited set ofnarrowband wavelengths comprises a first set of wavelengthscorresponding to but not matching pass areas of a filter disposed on afirst lens of the glasses and a second set of wavelengths correspondingto but not matching pass areas of a filter disposed on a second lens ofthe glasses.
 23. The glasses according to claim 22, wherein the passareas of the filters encompass and are shifted relative to theircorresponding narrowband wavelengths.
 24. The glasses according to claim23, wherein the pass areas are shifted toward longer wavelengthsrelative to their corresponding narrowband wavelengths, the spectralproperties of the filters vary from one filter location to anotherlocation of the same filter.
 25. Glasses for viewing 3D images, theglasses comprising filters disposed on lenses of the glasses, thefilters comprising passbands having properties configured to pass aplurality of light wavelengths intended to carry the 3D images, andwherein a construction of the glasses and filters includes a combinationof more than one technique to reduce an effect of viewing angle relatedshifts of the passband properties.
 26. The glasses according to claim25, wherein the more than one technique includes a curvature of thelenses and an offset of passband properties relative to wavelengthsintended to be passed by the passband when viewed normally.
 27. Theglasses according to claim 25 wherein the more than one techniqueincludes a curvature of the lenses and a mismatch between properties ofpassbands and wavelengths intended to be passed through the passbands.28. The glasses according to claim 27, wherein the mismatch comprisesmore than one wavelength bands separated from each other and passedthrough a same passband of the filters.
 29. The glasses according toclaim 27, wherein the mismatch comprises a passband that encompasses andis offset relative to the wavelengths intended to be passed when viewedat normal angles of incidence through the glasses.
 30. The glassesaccording to claim 29, wherein the offset comprises a red shift ofpassband properties relative to the wavelengths intended to be passed.31. The glasses according to claim 30, further comprising a non-uniformbandwidth of guardbands between adjacent passbands of opposite channels.